1. Field of the Invention
The invention relates to current regulators and, more particularly, to a current regulating system comprising at least one series branch containing a linear series regulator for forming a manipulated variable signal, where a series regulator is connected to a semiconductor control element, which is connected to a supply voltage referred to ground, and an output voltage referenced to ground at the series regulator on the output side. The invention also relates to a method for regulating a current.
2. Description of the Invention There are numerous electrical and electronic applications that make current regulation necessary. For example, power supplies are known that regulate the current to output a constant current to one or more connected loads.
In addition, electronic protective devices are known that are used to safeguard one or more load circuits connected to a power supply. If a fault (e.g., a short-circuit) occurs in a load circuit, the electronic protective device limits the current for a short time (e.g., a few milliseconds) by current regulation and then turns off. The other load circuits continue to be supplied from the power supply. Also when momentary excess currents occur, for instance, when a load is switched on, electronic protective devices limit the current to a defined value.
In such applications, which only provide current limiting or current regulation for a short time, simple linear series regulators are mostly used. Such series regulators control a semiconductor control element, which absorbs energy for a short period to keep the current through a connected, faulty load at a defined value. The schematic layout of a corresponding current regulating system is shown in FIG. 1. In this circuit, a series branch for regulating a current through a connected load is provided at a supply voltage.
A reference value or setpoint value for regulating the current, and a current measurement value are referenced to the output voltage, which drops across the connected load. The series regulator is supplied here from an auxiliary voltage, which likewise has the output voltage as the reference potential. The auxiliary voltage is used to generate a sufficiently high manipulated variable signal between a control terminal (gate) and an output terminal (source) of the semiconductor control element.
If, for example, a plurality of series branches are connected in parallel to a supply voltage, a separate auxiliary voltage must be provided for each series regulator because each auxiliary voltage generally has a different output voltage as the reference potential.